Due to its location and geometry, the bilge area of aircraft serves as the destination for waste air with higher levels of, for example, waste heat, aromatics or smoke and as a collecting tank for accumulating liquids. For example, the waste water from drains, oil, grease, cleaning agents and condensate forming on the structure or in the insulating materials during temperature changes are accumulated in the bilge area. In order to prevent corrosion, the bilge area is only thermally insulated to a limited degree.
This means that a correspondingly higher expenditure is required for the thermal insulation of areas that lie directly adjacent to the bilge area, e.g., cargo compartments and underfloor areas.
The bilge area of aircraft usually contains pressure control valves for ensuring that the more polluted air accumulating in this area is permanently discharged from the aircraft fuselage. If the air quantity introduced into the bilge area during the various operating states on the ground and in the air is exactly laid out, it is possible to prevent the air in the bilge area from being recirculated into the cabin.
In systems used so far, the additional heating of the bilge area with a hot air flow consequently is only possible as long as no recirculation takes place from the bilge area into the cargo compartments, underfloor areas or cabin areas. The air quantity that can be introduced into the bilge area is essentially defined by the air quantity being discharged from the aircraft fuselage by the pressure control valve.